The use of a so-called "chassis dynamometer" with inertial weights to measure the acceleration and deceleration performance of an automobile or other vehicle has long been known (see Knudsen R. F., "Inertia Electronically", ISA Journal, April 1958, Vol. 5. No. 4, PP 52-54). Further dynamometers are described in Patent Specification Nos. GB-A-1297813, 1604320 and 2149520, U.S. Pat. Nos. 3,590,633, 3,780,573 and 4,359,896 and in Roberts J. B., "An Advanced High-Speed Dynamometer for Testing Aircraft Tyres, Wheels and Brakes", read before the Applied Mechanics Group of the Institution of Mechanical Engineers on 10 Apr. 1974.
In a conventional dynamometer such as that described by Roberts supra the forces on the tire, wheel and brake under test are measured by load cells attached in the load path from hydraulic ram means of the loading head and a sliding carriage thereof. This invention is concerned with the problem of improving the accuracy with which loads and moments on the test subject can be determined and of enabling corresponding loads and moments in the group plane to be determined. It is further concerned with providing such a system in which loads in and moments about the spin axis and a pair of orthogonal axes are determined.